Guide Cam for OAG

[SteveBz]

Hi Guys,
The ZWO ASI 290 or QHYiii 290 are obviously ideal for OAG. But there seem to be other less expensive options too, like the DSI II pro. The QHY5L II m is also about half the price of the 290s. Does anyone have experience of the QHY5L II in OAG? I really don't want to be rotating the prism to find a star, just click and go.

It also has the advantage of having no flanges so I could slide it right in or out of a helical focuser to find focus.

Regards,

Steve.

 

Edited August 17, 2020 by SteveBz

[rl]

The QHY5L2 is a very good OAG camera for the reasons you point out. even if the chip is a bit small. Working at 900 - 1200 mm focal length I've had issues occasionally finding a guide star. No issues in the galactic plane, but in some of the sparse parts of Ursa Major I've had to move the main object slightly off centre just to find a guide star. 

If I remember correctly, the connectors on the back of the QHY5L2 had a bit of a reputation for not being the best, but I've never had any issues myself. But I always allow a lot of strain relief.

[SteveBz]

39 minutes ago, rl said:

The QHY5L2 is a very good OAG camera for the reasons you point out. even if the chip is a bit small. Working at 900 - 1200 mm focal length I've had issues occasionally finding a guide star. No issues in the galactic plane, but in some of the sparse parts of Ursa Major I've had to move the main object slightly off centre just to find a guide star. 

If I remember correctly, the connectors on the back of the QHY5L2 had a bit of a reputation for not being the best, but I've never had any issues myself. But I always allow a lot of strain relief.

Thanks for this.  And no need to rotate the OAG, just a little nudge occasionally on RA or DEC at high Declination?

[rl]

Depends on your luck, and how far you are prepared to move the main subject off centre. So far I have never had to rotate (and refocus)...just moving a bit has been enough. But I've often had only one or two stars in the OAG field and they're frequently towards the edge. ..one day it's going to happen. On my main camera, (QHY183) I think all 3 OAG positions are available. On the DSLR, bits of camera clash for 2 out of 3 alternatives. 

The question is..what's the alternative? Guidescopes have their own issues with Newts at this focal length. A bigger  chip in the guidecam will always help....at extra cost as you have pointed out. But it is probably the only realistic way of improving the situation.